Car in limp mode. Need some help | FerrariChat
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Car in limp mode. Need some help

Discussion in '348/355' started by Shootfighter65, Sep 11, 2015.

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  1. Shootfighter65

    Shootfighter65 Formula 3

    May 13, 2014
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    Randy..alluneedtokno
    #1 Shootfighter65, Sep 11, 2015
    Last edited by a moderator: Sep 7, 2017
    My car is going straight to a solid slow down and limp mode with no warning. I will do this after 3-4 min of driving. The. In a mile or so go to normal only for it to pop up and go into limp mode. Not sure where to start but her is the codes it throws. There is no cel just these codes
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  2. Drock28

    Drock28 Formula 3

    Jan 13, 2013
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    #2 Drock28, Sep 11, 2015
    well as we all know the sdl system is related to cat temps.

    if your car is going to solid sdl right at or shortly after start up then we know it's not an overheating cat.

    so the usual suspect for this glitch is something electrical with the cat ecu's or thermo probes.

    unless of course you happen to have a glogged cat.
    then perhaps it's indeed overheating quickly in those first few miles.

    so I guess first thing to do is remove and inspect your cats.
     
  3. Eric C

    Eric C F1 World Champ
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    #3 Eric C, Sep 11, 2015
    I didn't think SDL's cause codes to trigger?
     
  4. Shootfighter65

    Shootfighter65 Formula 3

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    #4 Shootfighter65, Sep 11, 2015
    They are new hyper-flows. I don't think it's the cats. If it was it wouldn't be intermittent it comes on as a solid light and limp mode no warning. But a minute down the road light goes out and no limp mode. Can a O2 sensors cause this? By pass valve not working? Could the thermo at the bypass? If it is a thermo how do I tell which bank is having the problem?
     
  5. Shootfighter65

    Shootfighter65 Formula 3

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    #5 Shootfighter65, Sep 11, 2015
    I didn't think so either but I thought the codes might give some insight
     
  6. yelcab

    yelcab F1 World Champ
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    #6 yelcab, Sep 11, 2015
    Do yourself a favor and get a IR thermometer. When the SDL is on solid, point it at the offending cat and measure the temp.

    You never know. That will rule out the cats.
     
  7. Shootfighter65

    Shootfighter65 Formula 3

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    #7 Shootfighter65, Sep 11, 2015
    Drivers temp 265
    Passenger 263 with slow down light on not blinking solid and car went into limp mode. Bypass valve has no vacuum
     
  8. yelcab

    yelcab F1 World Champ
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    #8 yelcab, Sep 11, 2015
    OK, then one of your 3 TCU is acting up. You need to probe it and find out which one needs replacing
     
  9. Shootfighter65

    Shootfighter65 Formula 3

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    #9 Shootfighter65, Sep 11, 2015
    Exactly how do I do that? I am thinking the passenger side in the back because the bypass valve isn't working. Can I unplug and drive the car one ecu at a time and see if problem goes away?
     
  10. yelcab

    yelcab F1 World Champ
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    #10 yelcab, Sep 11, 2015
    Do you know if any of your TCU has been replaced? If they are green/black in color, then they have been replaced. if they are black/black, then they are bad.
     
  11. Eric C

    Eric C F1 World Champ
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    #11 Eric C, Sep 11, 2015
    You running midpipes or anything? Did the car recently get wet or rained on?
     
  12. Shootfighter65

    Shootfighter65 Formula 3

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    #12 Shootfighter65, Sep 11, 2015
    My car gets rained on often lol. It has green ecu. Can I disconnect them one at a time to see which one is bad?
     
  13. yelcab

    yelcab F1 World Champ
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    #13 yelcab, Sep 11, 2015
    Each TCU has a 4 pin connector attached to it: blank, ground, 12V,and signal.

    Probe the voltage between Grd and Signal, while there is a SDL on, see which one is close to 5V. That is the one to be replaced.
     
  14. Shootfighter65

    Shootfighter65 Formula 3

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    #14 Shootfighter65, Sep 12, 2015
    That might be hard with it being intermittent. Also tough to do when car is running. Anyway to tell which bank is being shut down?
     
  15. drbob101

    drbob101 F1 Rookie
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    #15 drbob101, Sep 12, 2015
    The best way to do this is to get positaps and tap the SDECU outputs with long leads into the car and drive around if you can with a DVOM and see the outputs real time. You will know immediately which SDECU is causing the problem and then you can swap or replace components (SDECU / TC) and chrvk your results real time by voltage output.

    This is a much more accurate way than waiting, hoping and guessing by using the SDL.
     

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